The present invention relates to vacuum brake boosters comprising a housing and a bent connecting element for connecting the vacuum brake booster to a vacuum source, wherein the connecting element comprises a first connecting piece which extends through an opening in the brake booster housing into a vacuum chamber of the vacuum brake booster, and a second connecting piece for connecting the connecting element to the vacuum source. The connecting element has a multi-part housing with a first housing part which carries the first connecting piece and a second housing part which carries the second connecting piece arranged at a first angle to the first connecting piece.
Vacuum brake boosters have long been known and nowadays are used in virtually every motor vehicle which is fitted with a hydraulic braking system. They are used to keep a force that is to be applied by the driver of a vehicle to actuate the braking system at a comfortable, relatively low level. To achieve this the brake booster adds an auxiliary force, also called a servo force, generated by the brake booster to the actuating force applied by a driver, so the brake actuating force available at the wheel brakes is considerably boosted compared with the force applied by the driver.
Said auxiliary force is generated by a pressure differential in the housing of the brake booster which acts on a moving wall which is arranged between a working chamber and a vacuum chamber of the brake booster. To control the level of the pressure differential, and therewith the size of the auxiliary force generated by the brake booster, a control valve is used which on the one hand, can connect the working chamber of the brake booster to atmospheric pressure (or with overpressure) and on the other hand can connect the vacuum chamber of the brake booster to the working chamber.
So a vacuum brake booster can function, during operation its vacuum chamber must be connected to a vacuum source which constantly maintains a certain vacuum with respect to atmospheric pressure in the vacuum chamber. A vacuum that prevails in the intake section of a motor vehicle internal-combustion engine is often used as the vacuum source; in newer vehicles with their relatively lightly throttled engines a separate vacuum pump is increasingly being used as the vacuum source however.
In each case the vacuum chamber must be fluidically connected to the vacuum source. As a rule a hose is used which leads from the connecting element that is on the brake booster for connection of the hose to the vacuum source. For reasons of space the connecting element often has a bent design.
Whereas previously usually resilient hose assemblies were used which extended from the connecting element to the vacuum source, nowadays non-resilient, pre-shaped hose assemblies are increasingly being used, of which one end is shrunk onto the second connecting piece of the connecting element. If non-resilient, pre-shaped connecting hose assemblies of this type are to be automatically assembled on a vacuum brake booster, it is important that with each vacuum brake booster of a series the connecting element always has the same position with respect to the corresponding end of the connecting hose assembly. This is not the case with conventional vacuum brake boosters with a bent connecting element for connecting the brake booster to a vacuum source. Instead, with vacuum brake boosters of this type known from the prior art the connecting element has to be rotated into an appropriate position before it is connected to the connecting hose assembly.
The invention is therefore based on the object of providing a vacuum brake booster with a bent connecting element that is used for connection to a vacuum source, wherein the connecting element is adapted to be brought into a predefined, desired position and then reliably retains this position.